Magnetic belt type of dictating and transcribing machine



Feb. 22, 1955 N. 1.. CONRAD MAGNETIC BELT TYPE OF DICTATING AND TRANSCRIBING MACHINE 5 Sheets-Sheet 1 Original Filed Dec. 9, 1949 mw V "W W II OIIHHII. w c WMW ||b||I w Q Q m Q 1 g Q Q Q Q N. L. CONRAD Feb. 22, 1955 MAGNETIC BELT TYPE OF DICTATING AND TRANSCRIBING MACHINE 5 Sheets-Sheet 2 Original Filed Dec. 9. 19

Feb. 22, 1955 N. 1... CONRAD 2,702,710

MAGNETIC BELT TYPE OF DICTATING AND TRANSCRIBING MACHINE Original Filed Dec. 9, 1949 6 Sheets-Sheet 3 I I 111! I,

Feb. 22, 1955 N. L. CONRAD 2,702,710

MAGNETIC BELT TYPE OF DICTATING AND TRANSCRIBING MACHINE Original Filed Dec. 9, 1949 5 Sheets-Sheet 4 IN VEN TOR. Woman/z Z [Ev/v ma DECE RSE} Feb. 22, 1955 N. L. CONRAD 2,702,710

MAGNETIC BELT TYPE OF DICTATING AND TRANSCRIBING MACHINE Original Filed. Dec. 9, 1949 5 Sheets-Sheet 5 INVENTOR. A ar/72am! flarzrczd,

DecEa Eh United States Patent MAGNETIC BELT TYPE OF DICTATING AND TRANSCRIBING MACHINE Norman L. Conrad, deceased, late of Park Ridge, lll., by Leona E. Conrad Norton, executrix, Arlington, CaliL, assignor, by mesne assignments, to Felt and Tarrant Manufacturing Company, Chicago, III., a corporation of Illinois a Continuation of abandoned application Serial No. 131,990, December 9, 1949. This application January 28, 1954, Serial No. 406,726

12 Claims. (Cl. 2744) belt structure.

The recording and reproducing head is caused to travel across the width of the belt during the rotation of the belt by the operation of a lead screw, and this lead screw predetermines the lateral spacing between successive convolutions of the helical magnetic track around the belt. It is desirable that there be some spacing between the adjacent convolutions or turns of this magnetic track. Inasmuch as there is no physical groove in the recording beltand no stylus or needle riding in sach a groove, the centering of the recording and reproducing head directly over the center of the magnetic sound track is made more difiicult, and hence some spacing is desirable to avoid the possibility of the head extending laterally beyond one track where it might overlap one or more adjacent tracks. Still further, the magnetic track itself may have some variations in width incident to the recording of different volumes of sound, frequencies, etc., and some space is desirable between adjacent tracksto avoid interference or interfringing of the variable fringe edges of adjacent tracks.

The presence of the space between successive turns of the magnetic sound track introduces complications as soon as the magnetic belt is taken off the dictating ma- I chine for placing on a transcribing machine, or is merely taken ofi either one of these machines for later replacing on that same machine. In either of these instances, it is possible for false indexing between the magnetic track and the travelling head to arise, i. e. for the recording or reproducing head to be in registration with the space between successive turns, rather than in registration with one of the turns of the magnetic track.

One of the principal objects of the present invention is to provide an improved indexing arrangement which will insure proper indexed relation between the magnetic track and the recording or reproducing head whenever the magnetic belt is placed back upon either the dictating machine or the reproducing machine. The magnetic belt travels as an endless loop over a driving roller and take-up roller, which latter roller is mounted for swinging movement relatively to the driving roller, as from an off position into an indexing or loading position, and thence into a normal operating position. The motor driven driving roller carries driving sprocket teeth which mesh with sprocket holes in the magnetic belt, so as to drive the belt at a constant speed, and this driving roller is synchronously geared to the feed screw which produces the horizontal traverse of the recording or reproducing head. One of the features of the improvedindexing arrangement is the provision of automatic mechanism which causes the driving roller to revolve automatically to exactly the same rotative indexing position and to come to a stop in that position whenever the pressure, is maintained by use of leverages.

2,702,710 Patented Feb. 22, 1955 take-up roller is swung downwardly from its off position to its indexing or loading position. This insures or facilitates the proper placing of the belt on the driving roller, so that the magnetic sound track in this belt will be properly synchronized or indexed relatively .to the horizontal traverse of the recording or reproducing head.

Another object of the invention is to provide an improved carriage design and head mounting for these magnetic belt recording or transcribing machines. The head pressure, as well as the longitudinal head drive The man ual operation of the head is greatly simplified, viz. pushing releases the drive, and upward lift engages a holding device to keep the head off the drive roller while applying the magnetic belt.

Another object of the invention is to provide an improved and simplified construction of back-spacer for back spacing the magnetic head manually.

Still another object of the invention is to provide a simple, quiet construction of drive clutch between the electric motor and the driving roller which will have a minimum of starting and stopping time.

Other objects, features and advantages of the invention will be apparent from the following detail description of one preferred embodiment thereof. lo the accompanying drawings illustrating such embodiment:

Figure 1 is a front elevational view of the machine showing theswingingly mounted take-up roller in its lower operative position with the magnetic belt in operativeposition upon the driving and take-up rollers;

Figure 2 is an end view, partly in elevation and partly in section, showing the take-up roller in its operative position, with the span of the magnetic belt travelling over the driving roller and take-up roller;

Figure 3 is another end view, mostly in section, showing the loading position and the off position of the takeup roller, and also illustrating the indexing arrangement which causes the driving roller to revolve to a predetermined indexing position whenever the take-up roller is moved from its off position to its indexing or loading position;

back-spacing mechanism;

Figure 5 is a fragmentary side elevational view of the improved clutch mechanism which controls the transmission of the drive from the electric motor to the driv' ing roller;

Figure 6 is a fragmentary transverse sectional view of this drive clutch, corresponding to a section taken approximatelyv on the plane of the line 6-6 of Figure 5;

Figure 7 is a fragmentary side elevational view of the travelling carriage and recording head; and

Figure 8 is a circuit diagram of the electrical instrumentalities of the machine.

The housing and all operating parts of the machine are preferably mounted upon a rectangular supporting base 15 which is shown in the form of a sheet inetai stamping, although it will be understood that this might be in the form of an ordinary casting, die casting or the like, if desired. Bolted or screwed to this base is a vertically extending-frame casting 16 which. is disposed crosswise of the base slightly to the left of the center of the base (Figures 1, 5 and 6). This transverse vertical frame casting supports the driving roller, lead screw, electric motor, and most of the operating parts. In addition, another frame casting 17 (Figure 2) is disposed at the right hand end of the machine for supporting the right hand ends of the lead screw and carriage supportshaft, as will be later described. Extending upwardly from the base 15 and enclosing the frame castings 16 and 117 is a housing 21 forming'a' closed compartment 22 (Figure l) at its left hand end for enclosing the electric motor, drive clutch and other operating mechanism: At the right hand side of the machine, the front wall of this housing 21 has a recessed set-back 23 (Figure 2) in which is disposed the driving roller 24, and into which is adapted to swing the take-up roller 25 when the latter is swung up to its off position, as shown in dotted lines in Figures 2 and 3. The endless magnetic belt which loops over these two rollers is indicated at 26. The top wall 28 of the housing terminates at the rear of this recessed set-back area 23 (see Figure 2), and a separate housing plate 31 extends downwardly and forwardly to the base of the main housing for closing off the back of this setback area 23. As shown in Figure 2, a horizontal slot 33 is defined between the front edge of the top housing wall 28 and the upper edge of the separate housing plate 31, and through this horizontal slot extends part of the traveling carriage 35 for mounting the recording or reproducing head 36. Disposed in rear of this slot 33 is the horizontal lead screw 41 which produces \the horizontal traverse of the carriage 35 and head 36 across the top face of the driving roller 24 and magnetic belt 26. The lead screw 41 is geared to rotate synchronously with the driving roller 24, and the rate of rotation and degree of pitch of this lead screw are proportioned so that each turn of the lead screw traverses the carriage 35 a distance slightly greater than the width of the magnetic sound track during each complete revolution of the magnetic belt 26. Thus, the desired spacing is maintained between adjacent turns of the magnetic track around the belt. In the construction illustrated, the lead screw travel of the head 36 across the width of the belt is arranged to occur from right to left, but this may, of course, be reversed in the design desired. As illustrative of typical proportions which have given satisfactory performance, the machine shown in the drawings has been operated with a belt approximately four inches wide and having a circumference or closed loop length of seventeen inches. The magnetic track that has been recorded on this belt is approximately ,6 of an inch (.020 inch) wide, having a spacing between successive turns or convolutions of approximately of an inch between centers. The tape or belt speed is approximately 3.4 inches per second, giving a total recording time of approximately eight minutes, leaving Ms inch margin at each side'of the belt. The belt which was used is of the type having either a plastic or paper base, coated on one side with a binder of minute isolated particles of iron oxide. Such belt might be coated on both sides and be reversible, if desired. It will be understood that the foregoing relations of direction of traverse, track width, track spacing, speed, belt composition, etc. have been given solely in an exemplary sense to enable those skilled in the art to practice the invention with greater facility, and are not intended to be limitative of the invention.

The left hand end of the driving roller 24 is mounted on a drive shaft 45 which is suitably journaled within the main vertical frame casting 16, but the right hand end of the drive roller is left free or unsupported, so that the closed loop of the magnetic belt 26 can be readily slipped over this roller from the right hand end. A ring of sprocket teeth 47 proiects peripherally from the left hand end of the drive roller 24 for engaging in sprocket holes 48 provided in the left hand edge of the magnetic belt. An index marker 49 is also provided at one predetermined point on this left hand end of the drive roller, and each magnetic belt 26 is also provided with a corresponding index marker 50 at one point along its left band edge, which two index markers are adapted to be brought into registering alignment in the act of placing the magnetic belt over the drive roller 24. That is to say, as the magnetic belt is slipped over the drive roller from the right hand end, the belt is so manipulated or positioned as to bring the index marker 50 of the belt into registration with the index marker 49 of the roller before the sprocket holes 48 of the belt are engaged over the sprocket teeth 47 of the roller. Thus, a predetermined indexed relation is established between the drive roller 24 and the magnetic belt 26 at the start of the recording operation and all the way across the width of the belt, which indexed relation should be duplicated whenever the belt is removed from the dictating machine and placed upon a transcribing machine for transcribing, or whenever the belt is removed from the dictating or transcribing machine and then placed back upon that same machine.

The take-up roller 25 also has its right hand end free or unsupported so as to permit the magnetic belt to be readily looped over this roller. Such take-up roller is rotatably mounted at the outer end of a swinging arm 55. A long supporting shaft 56 has one end staked or otherwise rigidly secured in the outer end of the swinging arm, and the take-up roller is revolvably supported on this shaft. The inner end of the swinging arm has pivotal mounting on a pivot stud 58 suitably secured to the right side of the frame casting 16. The SWlHgll'lg arm extends outwardly through a vertical clearance slot 59 formed in the left hand edge of the inclined housing plate 31, and has a range of movement of approximately 90 for carrying the take-up roller 25 into any one of the three positions A, B and C, illustrated in Figures 2 and 3. Position A, with the swinging arm extending substantially vertically, is the otfpositi on during which the machine is not operating or is being transported in a case. arm 55 inclines outwardly at a slight angle to the vertical, is the indexing or loading position, in which position the magnetic belt 26 is adapted to be placed over the drive roller 24 and take-up roller 25. Position C, with the swinging arm 55 extending outwardly substantially horizontally from the machine, is the normal operating position in which the recording and reproducing operations take place; The take-up roller and swinging arm are suspended in position C by the taut loop of the magnetic belt 26, whereby the weight of the roller 25 and arm 55 tend to keep the belt 26 at the desired tension over the upper surface of the driving roller 24 for proper recording and reproducing operations. The take-up roller is yieldingly held in positions A and B by a spring detent 61 comprising adetent arm 62 mounted on a pivot pin 63 suitably secured to the frame or casing of the machine. A tension spring 64 is hooked between a stationary anchoringpin 65 and an apertured lug 66 projecting from the arm 62 for normally swinging the detent arm upwardly. The outer end of the detent arm carries a laterally projecting pin or roller 67 adapted to have selective engagement in two angulrrly spaced recesses 68 and 69 formed in the lower end ofthe swinging arm 55. The take-up roller is yieldingly held in position A by the engagement of the detent stud 67 in recess 68 and is yieldingly held in position B by the engagement of this stud in recess 69 (Figure 2). A stop pin 70 limits the upward swinging movement of detent arm 62 so that when the take-up roller 25 is swung down to position C (FigureZ) the detent arm is incapable of engaging the roller carrying arm 55 so that take-up roller 25 is free to swing down and impose its weight on the loop of the belt.

The driving roller 24 and lead screw 41 are arranged to be driven by an suitable electric motor 71 (Figure 5 which may be a shaded pole induction motor, a selfstarting synchronous motor, a universal motor, or any other desired type. The motor is stationarily mounted within the closed left hand housing portion 22, and carries a small frictional driving roller 73 at one end. This driving roller 73 has continuous driving engagement against the periphery of a relatively large friction wheel 74, which periphery may be composed of rubber, impregnated felt or other suitable frictional material. The wheel 74 has a metallic hub 75 which is journaled upon a pivot pin 76 projecting laterally from the upper end of a swinging arm 77. Mounted on the pivot pin 76 and secured to the large wheel 74 is a smaller frictional clutching wheel 78 which is adapted to be swung into and out of clutching engagement with the periphery of another large friction wheel 79 mounted upon the drive roller shaft 45. The arm 77 is mounted to have freedom for swinging movement and also endwise sliding movement, such being accomplished by providing a slot 82 in the lower end of the arm engaging over a stationary mounting pin 83. Normally, the arm 77 occupies the position illustrated in Figure 6, with the clutching roller 78 out of engagement with the large driven wheel 79. Movement of the arm 77 toward the right causes the continuously rotating driven wheel 74 to ride up to a higher position on the small motor driven roller 73, whereby the clutching wheel 78 is swung upwardly and toward the right for movement into clutching engagement with the periphery of the large driven wheel 79. Such clutching engagement is effected by the energization of an electromagnet 85 suitably mounted below and in front of these driving wheels. An armature 86 is pivotally mounted upon a supporting bracket 87 projecting from the electromagnet core, and a tension spring 89 is arranged to normally retain the armature 86 in its retracted position. A resilient motion transmitting link 91 has one end hooked to an aperture in the armature 86 and has its other end hooked to an aperture 93 in the swinging arm 77. The motion transmitting link 91 may have a coiled loop Position B (Figure 3), wherein the swinging large driven wheel 79 for transmitting or a hair-pin loop formed therein, to transmit a resilient or yielding pressure from the armature 86 to the swinging arm 77. When the electro-magnet 85 is energized, the

arm 77 is immediately moved laterally and upwardly in the manner described above for causing the clutching roller 78 to move into clutching engagement with the a drive to the driving roller 24. The energizing circuit for the electromagnet 85 and the controls for governing the clutching operation will be later described in connection with the circuit diagram of Figure 8.

As previously described, the lead screw 41 is driven concurrently with the driving roller 24 whenever driving rotation is transmitted to the roller through the above described clutch mechanism. This is accomplished through the train of spur gears illustrated in Figures and 6. A spur pinion 94 on the driving roller shaft 45 meshes with a large'idler gear 95 which is journaled on a pivot pin 96 extending laterally from the frame casting 16. Driven by the large idler gear 95 isa smaller idler gear 97 which meshes with a driven spur gear 98 secured to the outer end of the lead screw 41. If desired, the driven spur gear 98 may be secured to the end of the lead screw through a releasable clamping screw 99 for enabling angular adjustments to be made between the timed rotation of the indexing marker 49 on the drive roller and the turns of the lead screw 41. As shown in Figure 5, one or more bosses 105 project laterally from the frame casting 16, and secured to the outer ends of these bosses is a journal bracket 107. The bracket 107 carries a journal 108 in which the end of the drive roller shaft 45 is journaled, thereby affording two laterally spaced points of bearing support for the shaft 45 to sustain the radial loads imposed by the overhang of the driving roller 24. End play of the driving roller 24 and its mounting shaft 45 is eliminated by an end play spring 111 in the form of a leaf spring which is secured to the bracket 107 and has a resilient end bearing constantly against the projecting end of the shaft 45. Likewise, end play of the lead screw 41 is eliminated by a leaf spring 112 bearing against its right end (Fig. 2). Also mounted in the frame casting 16, slightly above the lead screw 41, is a carriage support shaft 114 which functions as a guideway along which the carriage 35 is adapted to slide. The opposite ends of the lead screw 41 and guide shaft 114 are mounted in the outer frame bracket 17, shown in Figure 2.

Referring now to Figures 2 and 7, the carriage 35 comprises a relatively long guide tube 117 which has a snug sliding fit over the guide rod 114. Fulcrum blocks 118 project laterally from opposite sides of the carriage block 35 for tiltably supporting the recording and reproducing head 36. Extending'rearwardly from the head 36 is an inverted channel-shaped arm 121 having fulcrurri notches 122 formed in the lower edges of the channel flanges, these notches having fulcrum seating on the fulcrum blocks 118. Part of the weight of the head 36 and arm 121 is counterbalanced by a tension spring 124 which has its lower end hooked to the carriage at 125 and has its upper end hooked to the rear end of the arm 121 at 126. Anchored in the carriage 35 and extending freely up through a hole in the arm 121 is a screw 131 over which is adapted to hook a curved detent spring 132 secured to the upper side of the arm 121. A finger piece 133 projects forwardly from the head 36, and by pushing upwardly under this finger piece the detent spring 132 can be hooked over the .top of the screw 131 for holding the head in elevated position when applying or removing tapes or .be slid back to the startmfg that the travelling carriage and recording head can then point or' to any other point along the line of traverse o the carriage and head.

Referring now to the back-spacing mechanism illustrated in Figure 4, this mechanism comprises a horizontally extending back-spacing bar 141 disposed directly below the lead screw 41 and having back-spacing teeth 142 formed in its forward edge. These teeth are adapted to effect back-spacing engagement with a back-spacer bar 143 extending downwardly from the arm 135 of carriage 35. Normally, the teeth 142 are out of engagement with the back-spacer bar or lug 143, so that they do not interfere with the normal traverse of the carriage along the lead screw. It is only when the back-spacer bar 141 is swung forwardly and oscillated longitudinally that the teeth 142 engage the back-spacer lug 143. The combined sidewise and endwise movement of the back-spacer bar 141 is produced by swinging links 146, 146' which are pivotally connected to the bar at 147, 147.

These links have pivotal mounting on stationary supporting pivots 148, 148' carried by brackets 149 and 150 secured to the frame or housing of the machine. A tension spring 151 connected between the bar 141 and bracket 150 tends normally to hold the bar 141 oscillated rearwardly and to the left, as shown in Figure 4. The mounting link 146 has an extension arm 153 in which is mounted a button or operating head 154 which projects laterally from the right hand side of the housing 21. The user of the machine can back-space the carriage 35 and head 36 by merely pressing inwardly on the actuating button 155. He may perform successive back-spacing operations by repeatedly depressingthe button 155. The range of movement of the bar 141 is preferably limited by arm 157 projecting from the other mounting link 146 and having a down-turned lug at its end which plays within a motion limiting slot 159 in the bracket 150. It will be understood that the motion of the back-spacing bar 141 in a direction forwardly and toward the right serves first to engage one of its teeth 142 with the back-spacing lug 143, and to then rock the carriage and recording head in a clockwise direction around the guide rod ,114for belts to or from the driving roll 24. Extending downhalf threads therein for engaging with the threads on the lead screw 41. The overhanging weight of the head 36 acts through the spring 124 to swivel the carriage 35 in a counter-clockwise direction around the cylindrical guide rod 114, so as, normally, to hold the half thread portion 136 of the arm 135 pressed into engagement with the threads of the lead screw. Thus, part of the overhang ing weight of the head 36 holds the head lightly pressed against the tape 26, and the other part of this weight is transmitted through the spring 124 to hold the half-nut 136 pressed against the lead screw 41. When the finger piece 133 and head 36 are swung upwardly to their uppermost positions the half thread portion 136 is swung forwardly out of mesh with the threads on the lead screw, so

freeing the half-nut portion 137 from the lead screw, the continued motion of the back-space bar to the right serving to slide the carriage and recording head to the right a distance of one track width. if desired, the back-spacing bar 141 might also be arranged to be operated electromagnetically by a solenoid or the like, in response to a foot switch placed on the floor, such being particularly desirable in the case of transcribing machines where the stenographer will want to back-space without taking her hands from the typewriter keyboard.

Referring now to the automatic tripping mechanism which trips the cycling switch for obtaining an automatic indexing operation of the drive roller 24 each time that the take-up roller 25 is moved from position A to position B, this mechanism comprises a slide link 164 ar-.

' of the link lies in the path of the swinging arm 55. When the take-up roller is swung upwardly and inwardly to off-position A, the arm 55 strikes lug 167 and pushes the sliding link 164 inwardly to the position shown in Figure 3. Projecting from the link 164 is a switch actuating lug 168, having an insulating sheath, which is adapted to engage the back side of a movable contact spring 171 when the link 164 is oscillated forwardly. Such en gagement of the lug against the contact spring 171 separates that spring from its cooperating contact spring 172, which springs constitute the cycling switch for interrupting the energization of the electro-magnet when the indexing marker 49 on the drive roller is in its predetermined indexing position, substantially as shown in end of the spring hooks to a stationary anchoring pin 183, and the arrangement of lug 181 and pin 183 is such that the spring 182 has an over-center biasing action tending to snap to one side or the other across the center of the mounting pivot 178. Extending upwardly and rearwardly from the crank member 175 is another apertured lug or arm 185, and projecting laterally from such arm 185 is a stop lug 186. These cooperate with a pivoted cam trigger 188 having a hub portion 189 mounted for independent pivoting movement on the pivot pin 178 alongside the crank member 175. A tension spring 191 is connected between the apertured arm 185 and the trigger 188, and tends normally to hold the trigger swung toward the right into abutment against the end of the stop lug 186. A laterally turned end 192 at the top of the trigger 188 normally lies within the path of a tripping cam 194 which rotates continuously with the lead screw 41. As viewed in Figure 3, the lead screw 41 and the cam 194 rotate in the counter-clockwise direction indicated by the arrow, and this causes the radially extending leading edge of the cam 194 to engage the trigger 188 and oscillate it toward the right whenever the trigger is in the path to be intersected by the cam 194. Such oscillation of the trigger 188 toward the right (in a clockwise direction around pivot 178), causes the crank member 175 to swing in such direction as to thrust the slide link 164 toward the left in its switch opening direction. This motion is merely initiated by the trigger 188. and is completed by the over-center snap action of the over-center biasing spring 182. Thus, very shortly after the cam 194 starts oscillating the trigger 188, the biasing spring produces an over-center snap operation for quickly opening the cycling switch 171, 172 at a predetermined point in the rotation of the driving roller 24. This predetermined point is that point at which the indexing marker arrives at the indexing position shown approximately in Figure l. The opening of the cycling switch 171, 172 de-energizes the electro-magnet 85 and immediately interrupts the motor drive to the driving roller by permitting separation of the clutching wheels 78 and 79. This automatic cycling and indexing operation occurs each time that the take-up roller 25 is moved outwardly from position A to position B. In the reverse operation of swinging the take-up roller back into its offposition A, the slide link 164 is pushed inwardly and the crank member 175 is oscillated in the reverse direction for carrying the over-center biasing spring 182 to the opposite side of its dead center position, whereupon this biasing spring quickly snaps the crank member 175 and trigger 188 back to the normal position shown in Figure 3. The one-way yielding relation which the stop lug 186 and spring 191 establish between crank member 175 and trigger 188 prevents breakage of the parts if the operator should manually rotate the drum 24 backwardly to its indexed position.

The movement of the take-up roller 25 from its off position A into its loading position B is also arranged to close a main supply switch for energizing the electron tubes and other electrical apparatus. This is accomplished through a second slide link 199 mounted above the slide link 164. Slots 201 in this link have sliding engagement over headed guide pins 202 extending from the frame casting 16. A laterally projecting lug 204 on the front end of the slide link is adapted to be engaged by the edge of the swinging arm 55 and to be thrust inwardly thereby whenever the take-up roller is swung into its off position A. An insulated lug 206 projecting from the slide link 199 is adapted to impart switch opening movement to a contact spring 207 which normally tends to engage with a stationary contact spring 208. When the take-up roller is in its off position A the link 199 occupies its inner position, at which time contact spring 207 is separated from contact spring 208. When the take-up roller is swung outwardly to its loading position the pressure of spring 207 slides the link 199 outwardly and the two contact springs come into circuit closing engagement.

Protruding through the end wall of the casing 21, preferably at the right hand end. is a manually actuated knob 210 for rotating the transfer switch 210 which converts the machine from a recording operation to a reproducing operation, or vice versa. This switch is preferably of a rotary type, and by turning the knob 210 the switch can be quickly oscillated between either of two different positions. The switching and selecting contacts controlled by this switch knob 210 are disposed withinthe housing, and the switching and controlling functions performed thereby will now be described in connection with the circuit diagram of Figure 8.

In this circuit diagram, the rotating elements of the switch are indicated by the four contacting segmentsSa, Sb, Sc and Sd which are adapted to have selective switching engagement with eleven stationary contacts S1 to S11, inclusive. The segment Sd and contacts S2 and S4, shown in dotted lines, are on the back side of the switching disk. The switch is shown in the transcribe or reproduce positon. The audio or amplifying circuit preferably employs a conventional voltage amplifier, such as the tube designated 12817, and an output amplifier, such as the tube designated 1215. The third tube 70L7 is a combined half-wave rectifier and beam power output amplifier. These tubes are supported upon a shelf 214 in the rear of the housing 21 (Fig. 2). The input transformer is designated T1, the amplifier output transformer T2, and the oscillator transformer T3. An earphone jack E] is adapted to be connected to the secondary of transformer T2 through switch contacts S10 and S11, and network R1, Cl. A four-contact jack type of connector 215 establishes connection with a microphone M and a control switch CS, such as a hand switch, foot switch or the like. The recording head 36 has voice coil 36', and RF bias and erase coil 36".

It will be seen from Figure 8 that the manual selecting switch 210 controls the connection of the microphone from amplifier input to output when used as a loud speaking unit; it controls the RF bias and erase coils 36' and 36" in the recording head 36; it transfers the connection of the recording head from the amplifier output to the amplifier input; it controls the oscillator circuit through the oscillator side of tube 7017; and it controls the amplifier output to the earphone.

The switching is unique in that it utilizes low impedance circuits. The recording and playback head 36, microphone M and earphone are all low impedance. This is advantageous to prevent feedback in the switching circuits, as well as to isolate the universal amplifier from the external circuits for safety reasons. The low impedance also avoids the necessity of shielding the wires which connect the external parts. The input transformer T1 is of the hum bucking type to reduce hum pick-up from the motor 71.

When the take-up roller 25 and arm 55 are swung forwardly from off-position A to loading position B, the switch 207208 is closed, thereby completing the circuit to the heaters of the three electron tubes; to the electric motor 71; and to the plate of the rectifier side of tube 70L7. Afer the tubes have heated to the point that electron how is taking place from the cathode of the rectifier half of tube '70L7, a direct current circuit is formed from the rectifier through cycling switch 171- 172 and the winding of electro-magnet 85. The energizing of this winding attracts the armature 86, causing engagement of the friction clutch 78-79. Thereupon, the motor drive starts rotation of the drive roller 24, which continues until the automatic indexing mechanism opens the switch 171172 for stopping the drive roller at the indexing point illustrated in Figure l, as previously described. It is at this point that the magnetic belt 26 is applied to the rollers 24 and 25, with the indexing marker 50 on the belt in registry with the indexing marker 49 on the driving roller, following which the take-up roller 25 is swung down to operating position C for keeping the belt taut. The drive roller 24 will not start again until the circuit of electro-magnet 85 is again closed either through the control switch CS on the microphone M or in a floor control unit, or through switch 171172.

For transposing the machine to dictation after auto matic indexing mechanism has gone through its cycle,

the manual transposing switch 210 is turned clockwise to the dictating position, as viewed in Figure 8. This connects the microphone M through switch contacts S5 and S3 to the input transformer T1. The amplifier output transformer T2 is connected through network R1, C1 and switch contacts S11 and S1 to the voice coil 36 in the recording head 36. Switch contact S2 is a common return, and this contact is connected through switch contact S4 with the oscillator cathode of tube 70L7. The oscillator transformer T3 is connected through switch contacts S7 and S8 to the bias and erase coil 36" in the recordiug head 3 6. Speaking into the microphone M causes magnetic lines to be produced in the magnetic path of the recording head 36, This magnetizes the recording media in the belt 26 in accordance with the voice of the recording head 36 are well known to those skilled in the art.

Having illustrated and described what is regarded to be the preferred embodiments of the invention, nevertheless it will be understood that such are merely exemplary and that numerous modifications and rearrangements may be made therein without departing from the essence of the invention. 1

What is claimed is:

1. In a magnetic belt type of recording machine, the combination of driving means for driving an endless magnetic belt, take-up means on a separate axis for receiving said magnetic belt, means mounting said take-up means for translational movement toward and away from said driving means, a recording head having magnetic recording means therein, a lead screw for causing transverse movement of said recording head across the belt to produce a magnetic track therein in the form of a helical series of turns, and indexing mechanism automatically responsive to the translational motion of said takeup means and the rotary motion of said lead screw for indexing the position of said driving means relatively to the machine to facilitate proper replacement of the belt on the machine after it has been removed therefrom following a recording operation.

2 In a magnetic belt type of recording machine, the combination of a driving roller and a shiftably mounted take-up roller for supporting and driving an endless magnetic belt, an index marker on said driving roller adapted to cooperate with an index marker on said belt, a recording head having magnetic recording means therein, a lead screw for causing transverse movement of said recording head across the belt to produce a magnetic track therein in the form of a helical series of turns, and indexing mechanism responsive to shifting movement of said take-up roller and to rotary motion of said lead screw for causing said driving roller to be automatically placed in an indexed position with the index marker therepower to said driving roller, for causing said driving roller automatically to come to a stop at a predetermined indexing position for receiving the indexed point of said belt at that position.

5 In a magnetic belt type of recording and/or reprodu ci ng machine, the combination of a driving roller for driv ng an endless magnetic belt, a take-up rollerifor receiving the loop of said endless belt, means supporting said take-up roller for shifting movement into and out of a belt receiving position, an index marker on said roller and a cooperating index marker on said belt, a recording head having magnetic recording means therein, a lead screw for causing transverse movement of said head across said belt to produce a magnetic track therein in the form of a helical series of turns, an electric motor for driving said driving roller and lead screw, an electrically controlled clutch for controlling the drive to said on in a substantially predetermined position preparatory to receiving the belt.

3. in a magnetic belt type of recording machine, the combination of an endless magnetic belt having an index marker thereon, a driving roller and a take-up roller adapted toreceive the magnetic belt, said driving roller having an index marker thereon for cooperating with the 1 index marker on said belt, means mounting said take-up roller for relative translational movement toward and away from said driving roller, means for transmitting a drive to said driving roller, a recording head, feeding means for feeding said recording head across the width of said-belt, and indexing mechanism automatically responsive to said relative translational motion of said takeup roller for interrupting the drive to said drivmg roller at a point of predetermined timing fo r caus1ng sa1d dr1ving roller to assume anindexed position with its index marker in a predetermined position relatively to the machine preparatory to receiving the magnetic belt.

4. In a magnetic belt type of recording and/or reproducing machine, the combination of a driving roller for driving an endless magnetic belt, a take-up roller for receiving the other end of the loop of said endless belt, means movablysupporting said take-up roller for shifting movement toward and away from said driving roller, an index marker on said driving roller adapted to register with an index marker on said belt when said belt is'in properly indexed position on said driving roller, a recording head having magnetic recording means therein, a lead screw for causing transverse movement of said head across said belt to produce a magnetic track therein in the form of a helical series of turns, a source of power for driving said driving roller and lead screw, and indexing mechanism responsive to shifting movement of said take-up roller and to rotation of said lead screw preparatory to starting a recording or reproducing operation and including switch means controlling the transmission of roller and lead screw, a switch controlling said clutch, and indexing mechanism responsive to shifting movement of said take-up roller into belt receiving position and to rotation of said lead screw preparatory to starting a recording or reproducing operation for actuating said switch to cause said driving roller to automatically come to a stop at a predetermined indexing position for receiving the indexed point of said belt in registration with the index marker on said drive roller.

6. In a magnetic belt type of recording and/or re producing machine, the combination of an endless mag,

netic belt having sprocket holes therein and carrying an index marker at one point, a driving roller having sprocket teeth engaging in said sprocket holes for driving said endless magnetic belt, a cooperating index' marker" on said driving roller, a recording head having magnetic recording means therein, a lead screw for causing transverse movement of said head across said belt to produce a magnetic track therein in the form of a helical :series of turns, a take-up roller for said belt mounted on a movable support for movement between an off-position, a belt loading position and a recording position relatively to said driving roller, an electric motor for driving said clutch controlling the transmission of a drive from said motor to said driving roller and lead screw, a switch controlling said clutch, a switch actuator for actuating said switch, means responsive to movement of said take-up roller to said belt loading position for causing an operating movement of said switch actuator to move said switch to a position for starting rotation of said lead screw, means responsive to rotation of said lead screw for causing an operating movement of said actuator to move said switch to another position for stopping said driving roller at an indexing point to facilitate placing the two index markers in registration when placing the belt on the machine, and means responsive to restoration of said take-up roller to its oif-position for causing a restoring movement of said switch actuator.

7. In a magnetic belt type of recording and/or reproducing machine, the combination of a driving roller for'driving an endless magnetic belt, a recording head having magnetic recording means therein, a lead screw for causing transverse movement of said across said belt to produce a magnetic track therein in the form of a helical series of turns, a take-up roller for said belt mounted on a swinging arm for movement between an oft-position, a belt loading position and a recording po sition relatively to said driving roller, an electric motor for drivmg said driving roller and lead screw, a main switch controlling said motor, means for causing said main switch to close for energizing the motor when said take-up roller is moved out of itsoif-position, an electrically controlled clutch governing the transmission of a drive from said motor to said driving roller and lead screw, an indexing switch controlling said clutch, a spring biased overcenter switch actuator for said switch, tripping means responsive to rotation of said lead screw for causing an operating movement of said actuator in one direction to open said indexing switch for stopping said driving roller at an indexing point, and means responslve to restoration of said take-up roller to its oilpositlon for causmg a restoring movement of said switch actuator.

8. In a magnetic belt type of recording machine, the combination of a driving roller and a shiftably mounted take-up roller for supporting and driving an endless magnetic belt, a recording head having magnetic recording means therein, said take-up roller being shiftable into and out of a belt receiving positron, a lead screw for -causing transverse movement of said recording head across the belt to produce a magnetic track therein in the form of a helical series of turns, belt driving means for transmitting a drive to said driving roller, and clutch mechanism for starting and stoppingsaid belt dr ving means, said clutch mechanism comprising a frictional driving roller arranged to be driven from a source of power, a frictional driven wheel operat1vely connected with said belt driving means, a frictional clutching dler comprising concentrically mounted large and small idler wheels, said large idler wheel maintain ng continuous engagement with the periphery of said frictional driving roller and said small idler wheel adapted to have frictional clutching engagement with the periphery of said frictional driven wheel, mounting means for said cl utch-. ing idler comprising a mounting pin, an arm having a slot therein rotatively and slidably mounted on said pm, said arm carrying said clutching idler, and the motion 01' said slot on said pin permitting combined swinging and shifting movement of said clutching idler into and out of frictional clutching engagement with the periphery of said frictional driven wheel around the periphery of said frictional driving roller, electro-magnetic control means for etfecting such combined swinging and shifting movement of said clutching idler, and switch means responsive to the shifting movement of said take-up roller controlling said electromagnetic control means.

9. In a magnetic belt type of recording and/or reproducing machine, the combination of a driving roller adapted to drive an endless magnetic belt, a lead screw arranged to rotate with said driving roller, a supporting guide shaft disposed above and parallel to said lead screw, a travelling carriage having sliding and swinging movement on said guide shaft and comprising a downwardly extending arm having a threaded half-nut on its lower portion adapted to engage with said lead screw for causing traverse of said carriage across the width of said belt, a recording head having magnetic recording means therein, pivot means at the rear of said carriage and disposed rearwardly of said guide shaft for pivotally mounting said recording head on said carriage so that it has overhang beyond said pivot means and guide shaft, and spring means connecting said head with said carriage in shunting relation to said pivot means whereby part of the overhanging weight of the head holds the head against the magnetic belt and whereby part of such overhanging weight is transmitted through said spring means to said downwardly extending arm to hold said half-nut pressed against said lead screw.

10. In a magnetic belt type of recording and/or reproducing machine, the combination of a driving roller adapted to drive an endless magnetic belt, a lead screw arranged to rotate with said driving roller, a supporting guide shaft disposed above and parallel to said lead screw, a travelling carriage having sliding and swinging movement on said guide shaft and comprising a downwardly extending arm having a threaded half-nut on its lower portion adapted to engage with said lead screw for causing traverse of said carriage across the width of said belt, a recording head having magnetic recording means therein, pivot means at the rear of said carriage and disposed rearwardly of said guide shaft for pivotally mounting said recording head on said carriage so that it has overhang beyond said pivot means, spring means connecting said head with said carriage to establish a pressure transmitting connection therebetween in shunt of said pivot means whereby part of the overhanging weight of the head holds the head against the magnetic belt and whereby part of such overhanging weight is transmitted through said spring means to said downwardly extending arm to hold sa1d half-nut pressed against said lead screw, and coopcrating detent devices on said carriage and on said recording head for holding said recording head in a raised positron out of contact with the magnetic belt during the operation of changing belts.

11. In a recording machine, the combination of an endless recording belt having sprocket holes therein and carrying an index mark at one point, a driving roller adapted to drive said endless recording belt, sprocket teeth on said roller adapted to engage the sprocket holes in said belt, an index mark on said roller adapted to cooperate with the index mark on said belt, an electric motor for driving said roller, a take-up roller over which the endless belt is also adapted to pass, movable mounting means for said take-up roller enabling it to have translational motion relatively to said driving roller, switch means responsive to such translational motion for controlling said electric motor, a recording head adapted to travel transversely across said belt for making a record therein, a lead screw rotating with said driving roller for causing traverse movement of said recording head, and indexing mechanisrn cooperating with the translational motion of said take-up roller and with the rotational motion of said lead screw for automatically interrupting the drive to said driving roller for causing said driving roller to automatically come to a stop with its index marker substantially at a predetermined indexing point on the machine preparatory to starting a recording operation.

12. In a recording machine, the combination of a driving roller for driving an endless recording belt, an index mark on said driving roller and a cooperating index mark on said belt, a recording head adapted to travel transversely across the Width of the-belt for making a record therein, a lead screw for causing such travelling movement of said recording head, an electric motor for driving said driving roller and lead screw, a take-up roller over which the loop of the endless belt is adapted to pass. mounting means for said take-up roller enabling it to have translational motion relatively to said driving roller, and means responsive to such translational motion for controlling the drive to said driving roller whereby to cause the driving roller to revolve to an indexing position and to stop in such position preparatory to receiving the belt for a recording operation with the index mark on the belt in registration with the index mark on said driving roller.

References Cited in the file of this patent UNITED STATES PATENTS 1,037,952 Menus Sept. 10, 1912 2,318,828 Yerkovich May 11, 1943 2,335,586 De Sart Nov. 30, 1943 2,341,468 Neumann Feb. 8, 1944 2,478,539 Leitner Aug. 9, 1949 2,530,029 Pond Nov. 14, 1950 FOREIGN PATENTS 617,199 Great Eritain Feb. 2, 1949 

